Pirates off the coast of Somalia attacked a US flagged freighter with rocket fire and automatic weapons Tuesday, but the vessel escaped with only minor damage, the ship owners said in a statement.

Pirates off the coast of Somalia attacked a US flagged freighter with rocket fire and automatic weapons Tuesday, but the vessel escaped with only minor damage, the ship owners said in a statement.

The Liberty Sun requested assistance of the US Navy "which dispatched forces to assist the crew and the vessel," the Liberty Maritime Corporation said in a statement, without saying how many Navy ships were involved or providing details of the rescue.

The attempted hijacking comes after a five-day standoff with pirates holding a US merchant captain on a lifeboat off the coast of Somalia. The standoff ended Sunday when snipers aboard a US Navy warship shot dead three captors, freeing the skipper unharmed.

The US Navy captured a fourth pirate. Area pirates threatened retaliation on US ships. "We are grateful and pleased that no one was injured and the crew and the ship are safe," the Lake Success, New York-based Liberty Maritime said in its brief statement.

"We have communicated with the families of the crew to inform them of these developments. "We commend the entire crew for its professionalism and poise under fire." The Liberty Sun was en route to Mombasa, Kenya, from Houston, Texas carrying food aid cargo for African nations.

Earlier this week it made a stop in Port Sudan, and on Tuesday was continuing its voyage when it came under pirate attack, the company said. At least 18 ships are being held by Somali pirates who hold more than 250 crewmen hostage.